Electrochemical Properties of Spark Plasma Sintered Oxide Dispersion Strengthened Steel

The benefits of spark plasma sintering (SPS) - fast heating time, low sintering temperature and short dwell time, provide opportunities for producing fine grained, dense consolidated alloys. Joule heating of powdered samples is achieved in SPS by a pulsed DC with uni-axial pressure to aid the sintering process. Oxide dispersion strengthened (ODS) steels are candidate cladding materials due to their resistance to radiation embrittlement, thermally induced creep, and swelling. An ODS alloy was fabricated by introducing yttria into a gas atomized powder, Fe81/16Cr/3Mo at 0.5 wt% and sintering at temperatures of 800, 900, and 1000 ^oC with sintering times of 5, 30 and 60 minutes. Analysis by electron backscatter diffraction demonstrated that sintering temperature and time influenced the microstructural distribution, the grain size and the grain boundary segregation of elements. Potentiodynamic polarization results indicated that the microstructure influenced the corrosion behavior of the samples in 3.5 wt% NaCl. Electrochemical impedance spectroscopic experiments were performed and the data analyzed with equivalent circuits to demonstrate the influence that the microstructure had on the electrochemical properties of the steels.